Question: What do the following two equations represent? $4x+4y = -2$ $-4x+4y = -1$
Solution: Putting the first equation in $y = mx + b$ form gives: $4x+4y = -2$ $4y = -4x-2$ $y = -1x - \dfrac{1}{2}$ Putting the second equation in $y = mx + b$ form gives: $-4x+4y = -1$ $4y = 4x-1$ $y = 1x - \dfrac{1}{4}$ The slopes are negative inverses of each other, so the lines are perpendicular.